Derivation of differential and integral method of displacement formula

Derivation of differential and integral method of displacement formula

X = V0 T + (1 / 2) a T ^ 2 in the high school physics stage, we should have learned such a basic knowledge: do V - t function image. Then the area of the figure surrounded by x = T0, x = t, X axis, and V-T curve is the displacement from t0 to t time

Calculus derivation of cylinder moment of inertia formula
Why is "R1 * R1 + R2 * R2" in the formula J = m / 2 * (R1 * R1 + R2 * R2) not subtraction but addition

J=∫r^2ρdv
=∫r^2ρdr*H*r*2pai
=ρ*H*2pai∫r^3dr
=ρ*H*2pai/4r^4(r2-→r1)
=[ρ*H*2pai]/4(r1^2-r2^2)(r1^2+r2^2)
=m/2(r1^2+r2^2)

How to draw the golden section of rectangle with aspect ratio?
The aspect ratio of a rectangle is about 0.618

First make a square ABCD, and then draw its diagonal AC, with a as the center of the circle and AC as the radius. Intersect AB extension line with E, AE is the length of the rectangle, ad is the width